This invention relates to a processing apparatus for performing processes, including a coating process and a developing process, on an object, such as a semiconductor wafer or an LCD (Liquid-Crystal Device) substrate.
The semiconductor device manufacturing processes include a series of steps including coating a semiconductor wafer, usually a silicon substrate, with a treatment solution, such as a photo photoresist solution, exposing the photo photoresist film with a reduced circuit pattern using photolithography, and developing the resulting photo photoresist film.
A processing system that effects such coating and development comprises a cassette station that picks out a semiconductor wafer from a cassette and brings it into the cassette, a cleaning unit that cleans the wafer, an adhesion unit that performs an adhesion process on the surface of the wafer, a cooling unit that cools the wafer to a specific temperature, a photoresist coating unit that coats the surface of the wafer with a photoresist solution, a baking unit that effects pre-baking and post-baking, that is, heats the wafer before and after coating the wafer with the photoresist solution periphery exposure unit that facilitates the removal of the photoresist from the periphery of the wafer, a wafer delivery table that is used to deliver the wafer to the adjacent exposure unit, and a developing unit that exposes the exposed wafer to a developing solution and thereby selectively dissolving the photoresist on the wafer into the developing solution. The processing unit is an integration of these component parts, which improves the working efficiency.
In a widely-used conventional processing system of this type, a wafer transport path is laid longitudinally in the center of the system, a plurality of units are provided on both sides of the transport path, with each unit facing the front, and a wafer carriage for carrying the wafer to each unit is allowed to move over the wafer transport path.
Because the individual processing units are arranged along the wafer transport path extending horizontally, the processing system is oblong. The system layout makes the space occupied by the entire system larger, resulting in an increase in the cost of the clean room. Particularly to increase the cleanness in the entire system or at each section by applying a vertical laminar flow to this type of processing system, the large space makes the initial cost and maintenance cost of the air conditioners or filters very high.
To overcome this problem, a processing system has been proposed where a wafer transport member is able to move vertically and rotate around the vertical axis and processing units are arranged. around the wafer transport member in multiple stages, as described in the Jpn. Pat. Appln. KOKAI Publication No. 4-85812. With such a processing system, the space occupied by the system is decreased, which reduces the cost of the clean room and speeds up the transport speed and access speed, improving the throughput.
In the processing system, there is a limit to the number of stacked units because of restrictions on the height of the clean room. Since there have been demands for a further improvement in the through-put, the processing system seems to have difficulty meeting the demands sufficiently. There has been another demand for the diversification of processing.
In a composite processing system that has various processing units in a single system, a photoresist coating process and a developing process are carried out independently in separate processing units. In the processing units, the waste liquor after the processing and the solvent atmosphere containing organic solvent in the processing chamber are directed out of the composite processing system through a waste liquor pipe and an exhaust pipe. The directed waste liquor and solvent atmosphere are collected into a waste liquor tank and exhaust tank through a waste liquor pipe and an exhaust pipe laid in the factory.
With the system constructed as described above, for example, should a fire break out in the factory, there is a fear that the fire will pass through the exhaust pipe filled with the solvent atmosphere and spread into the composite processing system. Moreover, should a fire start in the composite processing system, there is a possibility that the fire will pass through the exhaust pipe and spread throughout the factory.